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Subjects

Abstract

Interest in metal–organic open-framework structures has increased enormously in the past few years because of the potential benefits of using crystal engineering techniques to yield nanoporous materials with predictable structures and interesting properties. Here we report a new efficient methodology for the preparation of metal–organic open-framework magnetic structures based on the use of a persistent organic free radical (PTMTC), functionalized with three carboxylic groups. Using this approach, we create an open-framework structure Cu3(PTMTC)2(py)6(CH3CH2OH)2(H2O), which we call MOROF-1, combining very large pores (2.8–3.1 nm) with bulk magnetic ordering. MOROF-1 shows a reversible and highly selective solvent-induced 'shrinking–breathing' process involving large volume changes (25–35%) that strongly influence the magnetic properties of the material. This magnetic sponge-like behaviour could be the first stage of a new route towards magnetic solvent sensors.

Acknowledgements

This work was supported by the Programa Nacional de Materiales of the Dirección General de Investigación (Spain), under project MAGMOL. D.M. is grateful to the Generalitat de Catalunya for a predoctoral grant. We thank P. Gerbier of the Université Montpellier for TG-MS experiments and X. Alcobé of the Universitat de Barcelona for X-ray powder diffraction measurements.

Corresponding author

Supplementary information

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Figure 2S Reversible magnetic behavior of the amorphous and
evacuated phase in contact with ethanol liquid, plot of magnetization
value as a function of the applied field at a temperature of 2.5 KFigure 3S Plots of χ'MT (top) and χ"MT (bottom) as a function of the
temperature for MOROF-1 at the indicated frequenciesFigure 4S χT value as a function of the temperature for MOROF-1Figure 5S (Left) χT value as a function of the temperature for complex Cu(PTMMC)2(H2O)3.Figure 6S Powder X-ray diffractogram of MOROF-1 (red) and
MOOF-1 (black).Structure The crystal structure of MOROF-1.